Carburetor



Dec. 8, 1936. GRENAT 2,063,433

CARBURETOR Filed April 25, 1934 2 Sheets-Sheet 1 INVENTOR ATTO RN EYSDEC. 8, 1936. J J GRENAT 2,063,433.,

CARBURETOR Filed April 23, 1934 2 Sheets-Sheet 2 y 20 52 fIII/IIIIIIIIIATTORNEYS Patented Dec. 8, 1936 UNITED STATES PATENT OFFICE 12 Claims.

The present invention pertains to a novel car. buretor of a typeparticularly adapted for use on variable speed internal combustionengines.

The primary object of the present invention is to provide a carburetorespecially suited for automotive engines which will provide fuel economyat all speeds of operation without sacrificing power, acceleration, andsmoothness of operation. It is well known that fuel economy and maximumpower can only be attained when the fuel and air are mixed in thecarburetor in the correct proportions and conventional carburetors arenot con structed in a manner to control the mixture by maintaining aconstant ratio of air and fuel at all engine speeds. For example, thewell known plain tube carburetor lacks the flexibility which is theobjective of the present invention, the reason being that if the airstream capacity is made sufficient for high speed engine operation bythe use of a relatively large venturi it results in difliculty inattaining smooth engine performance at moderate speeds. turi is madesmaller to adapt the engine to moderate speeds, it must be small enoughto provide sufficient air stream velocity to insure vaporization of thefuel at moderate speeds, and is for this reason not efficient at highspeeds. The problem resulting from the demand for high speeds has led tothe universal adoption of a high speed carburetor and in order toprovide for moderate speed of operation accelerating pumps, or auxiliarydevices for squiring fuel into the mixing chamber, and so-called idlespeed jets have been provided because of the lack of sufficientdepression or suction in the engine manifold to lift the fuel from thenozzle in the normal manner.

Another object of the present invention is to devise a carburetorwherein means is provided for automatically varying the'velocity of theair,

stream relative to the fuel nozzle so that a constant ratio ismaintained between the air and fuel under all conditions of engineoperation. In other words the present carburetor is capable ofautomatically regulating the air stream velocity so as to provide themost efficient air and fuel mixture at all engine speeds, includingidling speed, maximum speed, and any speed between idling and maximum.Furthermore the present device automatically controls the air and fuelratio under abnormal conditions such as rapid opening of the throttlevalve and also when travelling at a moderate speed with the throttlewide open such as would occur in an automotive vehicle under heavy loador when travelling on an up grade.

On the other hand, if the ven- With the above and other ends in View theinvention consists in matters hereinafter set forth and moreparticularly pointed out in the appended claimspreference being had tothe accompanying drawings, in which Figure 1 is a vertical crosssection;

Figs. 2, 3 and 4 are cross sections taken on the lines 22, 3-3 and 4-4respectively of Fig. 1;

Fig. 5 is a plan of the fuel nozzle; and

,Figs. 6, 7 and 8 are vertical cross sections illustrating the parts indifferent positions.

Like characters of reference are employed throughout to designatecorresponding parts.

The numeral l designates a cylindrical body having its upper endprovided with means 2 facilitating its attachment to an intake manifoldof an internal combustion engine. The lower end 3, which is broken away,is adapted to be connected to the atmosphere through means of a suitableair filter and fire arrestor. Inasmuch as carburetors and their mannerof assembly on automotive vehicles are well known to those versed inthis particular art it has been deemed unnecessary to illustrate theintake manifold and the air filter. It is also well known that there arebut two substances passing through a carburetor, the air for combustionof the fuel, and the fuel itself, both the air and fuel being drawn fromthe carburetor, by the suction created by the pumping action of thepistons in the cylinders of the enginei The suction stroke of thepistons sets up apartial vacuum in the intake manifold and hereinafterthroughout the description and claims the condition in the intakemanifold, which will be .the same at or about the point A in the body I,will be termed depression. That part in the body ldesignated as B willbe termed the mixing chamber, and that part designated C will be alwayssubject to atmospheric pressure.

At one side ,ofthe body I is provided a fuel chamber 4 such as is commonto all types of carburetors. It consists of a chamber containing aneedle valve 5 operated by a float 6, the needle valve controlling thepassage of fuel from a supply pipe 1. The float rests upon the gasolineor fuel which is in the bowl 4 so that when the level of fuel in thebowl drops, the needle valve opens, and fuel is admitted through thesupply pipe 1 until the correct level is established, at which time thefloat has been raised to a position where it causes the needle valve toclose. The purpose of this construction is to maintain a constant headof fuel in the bowl at all times.

As is also common to all types of carburetors there is provided athrottle valve 8. This valve is of the well known butterfly type and isoperated in a manner well known in the art and therefore not shown here.The throttle valve 8 is located between that part of the body designatedA and the part designated B.

The present carburetor includes a specially designed fuel jet 9 havingan inlet I0 extending into the bowl 4. The fuel jet 9 has two nozzles IIand I2 extending in different directions, there being substantiallycircular openings in the ends of each nozzle. The nozzle II, when viewedin side elevation, is of arcuate formation and in addition to thecircular opening in the end thereof it is provided with a slot I3 in itsupper wall.

Pivotally supported by a shaft I4a in the body I is an air valve I4. Inmany respects the air valve I4 resembles a conventional butterfly valve,the exception being that it is of streamlined cross section and when inits closed position it is angularly disposed relative to the body I. Inother words the air valve I4 cannot be moved to a position where it liesin a true transverse plane relative to the body I. The air valve I4 isformed with a Venturi shaped opening I5 into which the nozzle IIextends, the parts being so proportioned that the nozzle barely reachesthrough the Venturi opening when the air valve is in its closed positionillustrated in Fig. 1.

The body I is formed with a tubular projection I 6, the axis of whichextends in a radial direction relative to the body I. On the outer endof the tubular projection is screwthreaded a hollow cap I? and aflexible diaphragm I8 has its edges interposed between the cap and theend of the projection. A rod I9 has one end connected to the diaphragmand its other end extends through a slot 28 in the wall of the body Iand connected to the air valve I4. A plate 2| is carried by the rod I9and is held in a position where it covers the slot 20 by a spring 22which is sleeved around the rod I9 so that it is slightly compressed byengagement of one end thereof with the diaphragm while its opposite endengages the plate 2|.

A passage 23 is formed in the wall of the body I and opens as at 24 intothe part of the interior of the body above the throttle valve 8 anddesignated A. The passage 23 extends through the wall of the tubularprojection I6 and communicates with an aperture 25, the aperture 25registering with a slot 26 which is in communication with the interiorof the cap IT. The wall of the body I is provided with a screwthreadedbore 21 communicating with the passage 23, the passage 23 preferablybeing formed with a slight restriction 28 directly opposite to the bore.Received in the bore 27 is an air bleeder 29 having an air bleedingpassage 31). In order to vary the bleeding capacity various bleeders aremade with different sized bleeding passages and the capacity is changedby removing the bleeder and inserting another of different capacity.

The wall of the body I is provided with an opening 3I which providescommunication between the mixing chamber B in the body I and theinterior of the tubular projection I6. The body I also has anotheropening 32 providing communication between the interior C of the body Iand the interior of the tubular projection I6. The opening 32 isnormally covered by a plate 33 having a spring 34 urging it toward itsclosed position. The plate 33 constitutes a backfire valve so that inthe event an explosion takes place in the intake manifold or part A ofthe body I or in the mixing chamber B the force of the back fire willnot harm the parts above described but will exhaust through the opening32 into the air supply C.

In describing the operation reference will first be had to Fig. 1wherein the parts are shown in their idle speed positions. The air valveI4 is so located that it completely closes the cylindrical body I andair entering the end 3 cannot pass through the carburetor except forthat amount which passes through the Venturi shaped opening I5. The airis caused to flow from the part c, through the Venturi opening I5,because of the fact that a depression exists in the part A and due tothe fact that the throttle valve 8 almost, but not completely, obstructsthe pas sage of air through the carburetor. Because of the fact that airat atmospheric pressure cannot rapidly dissipate the depression at Abecause of the throttle valve 8, the depression is greater in the part Athan it is in part B. Therefore the depression which is realized in thehollow cap I! through the passage 23, plus the pressure of the spring22, is sufiicient to overbalance the depression in the tubularprojection I6 (which depression is equal to that in the mixing chamberB) and move the diaphragm I8 to a position maintaining the air valve I4in its closed position. This balanced condition of the diaphragm existsregardless of the bleeder 29 whose function will become apparent as thedescription progresses. During this operation the slot I3 along the topof the nozzle II acts as an air bleed when the air valve I4 is in itsclosed position.

As the speed of the engine increases to what might be termed cruisingspeed the throttle valve 8 will be in approximately the positionillustrated in Fig. 6. With the throttle valve 3 in the positionillustrated in Fig. 6 very little difference exists between thedepression A and the depression B. The air bleeder 29 admits enough airat atmospheric pressure into the passage 23 to cause a differential indepressions on opposite sides of the diaphragm I8. That is to say thedepression in the tubular projection I6 is greater than the depressionin the cap I I and the diaphragm I8 is biased so as to move the rod I9which in turn causes pivotal movement of the air valve I4. As the airvalve I4 is thus opened the Venturi opening I5 passes backwardly overthe nozzle II and gradually reduces the capacity of the slot I3 as anair bleeder. A greater portion of the nozzle I I is exposed through theopening I5, or in other words is extended into the air stream passingaround the air valve, and a greater amount of fuel is thus supplied tothe increased volume of air passing through the carburetor. When the airvalve I4 is moved from its closed position an air flow takes place pastits upper end and the nozzle I2 is so positioned as to be in this airflow. Thus the nozzle I2 is out of action until the air valve I4 ispartly opened and functions to supply fuel from the time of partialmovement throughout the full speed range of the engine.

In Fig. '7 the parts ar in their positions incident to the highest speedof the engine, or in other words the throttle 8 is wide open. With thethrottle valve 8 wide open the conditions of depression in the portion Aand the mixing chamber B are the same. Therefore the depression in thetubular projection I6 is the same as that at the point 24 where thepassage 23 opens into the part A. The air bleeder 29 admits air atatmospheric pressure to the passage 23 and sumciently dissipates thedepression in the cap I! that the diaphragm I8 :is biasedsufiicientlynto move the air valve M to a position where it offers theleast amount of resistance to the air flow. When in this position astill greater amount of the slot l3 in the nozzle H is exposed to theair stream while the nozzle l2 remains exposed. It will be appreciatedthat the. spring 22, in order to permit such a function, is extremelylight, it having barely enough strength to hold the diaphragm and airvalve in their closed positions when the engine is at rest. However, theair bleeder, which permits atmospheric pressure to enter the passage 23,is an important factor, inasmuch as it gives the mixing chamber Bdepression the advantage over the depressionin the manifold and realizedat A and permits the mixing chamber depression to bias the diaphragm tomove the air valve to its open position.

Fig. 8 illustrates positions of the parts under abnormal conditions ofoperation of the engines. The conditions might be a heavy load on theautomotive vehicle or might result from travelling on an up-grade, orthey might result from rapid opening of the throttle valve. Under any ofthe above named conditions the engine is operating at a slower speedthan is ordinary for the amount of throttle opening. Therefore thepumping action of the pistons in the engine is not so great as at higherspeed and the depression in the portions A and B, although equal in bothplaces, is not as great as in the case of the wide open throttle shownin Fig. 7. The air bleeder 29 functions to dissipate the depression inthe cap I! and the depression in the tubular projection I6 accordinglybecomes overbalanced and tends to bias the diaphragm to move the airvalve [4 to a position where it ofiers a partial ob- 'struction to theair stream. In other words the air valve forms a restricted passageadjacent to the nozzles II and I2 and with a given volume of air passingthrough the carburetor in a given time it will be found that thevelocity of the air as it passes the nozzles is greater than at anyother point in the carburetor.

From the foregoing it becomes obvious that the function of the air valveis to provide an almost constant air stream velocity at the part of thecarburetor adjacent to the nozzles, regardless of variations in the.volume of air passing through the carburetor. The air valve is balancedin the air stream in such a way that the pull of the air stream directlystriking against it does not open or close it, the air valve beingoperated through its connection with the diaphragm. Therefore thevelocity of the air stream over the nozzles is controlled automaticallyby conditions set up within the carburetor under varying operatingconditions of an engine, or in other words the depression in the upperpart of the carburetor and the depression set up in the mixing chamberare the controlling factors.

When operating at moderate speed with the throttle part open, the airvalve will be maintained in a position which will result in justsufficient air stream velocity for good vaporization of the fuel pickedup from the nozzles, without obstructing the air stream to anydetrimental extent. This valve operating at any given engine speed willfind its most economical position automatically, which will be at thebalance of the diaphragm between the two depressions above and below thethrottle valve. The result is low fuel consumption in the engine andabsence of special arrangements or devices to furnish the mixture forlow or idle speeds and the absence of squirt guns and so calledaccelerator pumps. ufAlthough a specific embodiment of the presentinvention has been illustrated and described it will be understood thatvarious changes maybe made within the scope of the appended claimswithout departing from the spirit of the invention, and such changes arecontemplated.

What I claim is:- --l. In a carburetor, a fuel jet formed with a pair ofnozzles, an air valve, said air valve being adapted toclose off thepassage of air through said carburetor and to cover one of saidnozzleswhen in a closed position, said valve having a Venturi shaped openinginto which the other of said nozzles extends. a

2. In a carburetor, a fuel jet formed with a pair of nozzles, an airvalve, said air valve being adapted to close off the passage ofairthrough said carburetor and to cover one of said nozzles when in aclosed position, said valve having a Venturi shaped opening into whichthe other of said nozzles extends, and automatic means for regulatingthe position of said valve to permit passage of air around said valveand to uncover said first named nozzle. 3. In a carburetor having apassage wherein suction at one end creates an air stream therethrough,means for regulating the volume of the air stream, a fuel nozzlein saidpassage, adjustable means for restricting said passage at a pointadjacent to said nozzle to maintain a constant air velocity at thenozzle when the volume of air passing through said passage is varied bysaid first named means, and means responsive to pressure conditions onopposite sides of said means for regulating the air stream for actuatingsaid adjustable means.

4 In a carburetor wherein suction at one end creates an air streamthrough the same, a throttle in said carburetor for regulating thevolume of the air stream, a fuel nozzle in said carburetor, means formaintaining a constant air velocity adjacent to said nozzle when thevolume of the air stream is varied by said throttle, and movable meansadapted to move in response to the'changing pressure conditions onopposite sides of said throttle for actuating said adjustable means.

"5. In a carburetor having a passage wherein suction at one end createsan air stream therethrough, a fuel nozzle in said passage, means forregulating the volume of said air stream, said means being disposedbetween said nozzle and the suction end of said carburetor and beingadapted to create different pressures on opposite sides thereof, andmeans actuated by the different pressures on opposite sides of saidregulating means for restricting said passage at a point adjacent tosaid nozzle to maintain a constant air velocity at the nozzle when thevolume of the air stream changes.

6. In a carburetor having a passage wherein suction at one end createsan air stream there-- through, a fuel nozzle in said passage, means forregulating the volume of said air stream, said means being disposedbetween said nozzle and the suction end of said carburetor and beingadapted to create different pressure zones in said passage, means forrestricting said passage at a point adjacent to said nozzle, and meansconnected with said pressure zones and actuated by the difference inpressure therebetween for operating said means for restricting saidpassage whereby the latter maintains a constant air velocity when thevolume of the air stream is changed.

7. In a carburetor having a passage wherein suction at one end createsan air stream therethrough, a throttle for regulating the volume of saidair stream, said throttle being adapted to set up zones of difierentpressures on opposite sides thereof, a fuel nozzle having a plurality ofjets, a valve adapted to restrict said passage, said valve having aVenturi opening through which one of said jets extends and a portionnormally obstructing air flow adjacent to the other jet, and meansoperated by the difference in pressure between said zones forautomatically moving said valve for maintaining a constant air velocityat the nozzle when the volume of the air stream changes.

8. In a carburetor having a passage wherein suction at one end createsan air stream therethrough, a throttle for controlling the volume of theair stream, a fuel nozzle, a valve mounted in said passage to restrictthe same whereby to govern the velocity of the air stream at a point insaid passage adjacent to said nozzle, and means operted by pressureconditions set up in said passage on opposite sides of said throttle bymovement of said throttle, said means maintaining a constant airvelocity at the point of restriction when the volume of the air streamis changed by movement of said throttle.

9. In a carburetor having a passage wherein suction at one end createsan air stream therethrough, a nozzle in said passage, a valve spacedfrom the discharge end of said nozzle and adapted to regulate the volumeof the air stream, adjustable means adjacent to said nozzle and adaptedto be moved to regulate the velocity of the air stream at a zoneadjacent to the outlet of said nozzle, a chamber communicating with saidpassage on one side of said valve, a movable element in said chamberoperatively connected to said means adjacent said nozzle, and meansconnecting said chamber on the other side of said movable element tosaid passage on the other side of said valve, said last named meanshaving a restricted port opening into the atmosphere.

10. In a carburetor having a passage wherein suction at one end createsan air stream therethrough, a nozzle in said passage, a valve spacedfrom the discharge end of said nozzle and adapted to regulate the volumeof the air stream, adjustable means adjacent to said nozzle and adaptedto be moved to regulate the velocity of the air stream at a zoneadjacent to the outlet of said nozzle, a chamber communicating with saidpassage on one side of said valve, a movable element in said chamberoperatively connected to said means adjacent said nozzle, meansconnecting said chamber on the other side of said movable element tosaid passage on the other side of said valve, and means normally heldclosed by yieldable means for providing communication between saidchamber and said passage at a point to one side of said velocityregulating means when an abnormal high pressure is present in saidchamber.

11. In a carburetor having a passage wherein suction at one end createsan air stream therethrough, a valve in said passage for regulating thevolume of said air stream, a nozzle in said passage, a regulatingelement located adjacent to said nozzleand adapted to be moved toregulate the velocity of said air stream, a diaphragm chamber, adiaphragm in said chamber and connected to said regulating element,means providing communication between said chamber on one side of saiddiaphragm and said passage on one side of said valve, means providingcommunication between said chamber on the other side of said diaphragmand said passage on the other side of said valve, and a restricted portin said last named means opening into the atmosphere.

12. In a carburetor having a passage wherein suction at one end createsan air stream therethrough, a nozzle in said passage, a valve spacedfrom the discharge end of said nozzle and adapted to regulate the volumeof the air stream, adjustable means adjacent to said nozzle and adaptedto be moved to regulate the velocity of the air stream at a zoneadjacent to the outlet of said nozzle, a diaphragm chamber, a movablediaphragm in said chamber operatively connected to said adjustablemeans, means providing communication between said chamber on one side ofsaid diaphragm and said passage on one side of said valve, meansproviding communication between said chamber on the other side of saiddiaphragm and said passage at a point between said valve and saidadjustable means, and normally closed yieldable means adapted whenopened to provide communication between said chamber and said passage ata point on the opposite side of said movable element when an abnormallyhigh pressure is present in said chamber.

JOHN J. GRENAT.

